1. Field of the Invention
The present invention relates to a cable reel mounted on a steering apparatus of automobiles, and more particularly, it relates to an improvement in the connecting configuration between a flat cable accommodated in an annular hollow space formed between a stator and a rotor of a cable reel and an external wire connected with the rotor side.
2. Description of Background Information
As shown in FIG. 9, a conventional cable reel 51 includes a stator 52 including an outer peripheral wall 52a and a bottom wall 52b fastened to a steering column and a rotor 53 including an inner peripheral wall 53a and an upper wall 53b fastened to a steering wheel (handle). The stator 52 and rotor 53 are connected for relative rotation. A flexible flat cable 55, which is accommodated in a coiled manner in an annular recess 54 between the stator 52 and the rotor 53, is unwound and rewound in accordance with reciprocal rotation of the rotor 53 in conjunction with rotational movement of the steering wheel (hereinafter abbreviated as wheel).
With the aforementioned cable reel 51, a conductor 56 of flat cable 55 is connected with a wire 58 of a wire harness on a rotor side through an inner peripheral end 56a at an end of the coil, while an outer peripheral end 56b of a conductor 56 of flat cable 55 is also electrically connected with a wire harness on a stator side through the cable reel 51. Thus, electric devices, such as a turn signal indicator, etc. are electrically connected with a circuit on a car body side.
In the case of the conventional cable reel 51 previously adopted, a bus bar 57 disposed on a rotor 53 side is fastened to a base 61a of case 61 as shown in FIG. 10. A conductor 56 of flat cable 55 is welded to one end of the bus bar, and exposed core wires from wire ends are welded to the other end of the bus bar, and a cover 61b is provided thereto after welding. The case 61 is fastened by inter-fitting into a recess 53c provided at an inner peripheral position of the upper wall 53b of rotor 53.
The connecting structure between the flat cable and a wire at the conventional cable reel 51, however, requires a base 61a and a cover 61b hat cover the bus bar as well as a case receiving recess on a rotor side, which unavoidably leads to an increase in the number of components and assembly processes. In addition, due to the complicated mounting structure around the bus bar 57, there appear such problems as difficulty in correctly positioning the flat cable 55 and the dimension in an axial direction of rotor 53 becoming larger in height due to the dimensional tolerance that accumulates in a disposed position of the flat cable 55.
In addition, with an increase in the number of circuits, in the case of a connecting area located between external wires and a flat cable that requires two positions must be provided, a case 61 becomes necessary which covers a bus bar connecting a flat cable and a wire for every connection, thereby causing problems in increasing the number of components as well as the assembly processes.
Furthermore, because the interfitted area between the rotor and the stator is the center of coiling of the cable, the length of the flat cable must be greater in order to accommodate the necessary number of steering wheel rotations. Although it is preferable to maintain the length at a minimum, there is a problem that the length of the flat cable inherently becomes larger and at least occupies a protrusive space of the case at the connecting areas.
The present invention was developed to solve the above problems. Therefore a purpose of the present invention is to attain electric connection between a flat cable and an external cable through a bus bar without using a different case, thereby reducing the number of components and assembling processes.
According to an aspect of the present invention, a cable reel is provided including a rotor interlocked with a steering wheel and rotatably connected with a stator provided on a steering column, a flat cable is provided in a coiled manner in an annular hollow space provided by the stator and rotor, and an inner peripheral end of the flat cable is electrically connected with an external cable through a connector which extends from the rotor. Additionally, an upper wall of the rotor forms an inner cylinder and an upper wall of the annular hollow space, a bus bar is connected with each conductor on the inner peripheral end side of the flat cable and is secured to the upper wall of the rotor with an insert mold, and the conductors of the flat cable and an external cable are welded to the bus bar.
According to a further aspect of the present invention, because the bus bar functions as an electric relay electrically connecting the inside and outside of the cable reel and is insert molded on the upper wall of the rotor, a mounting case is unnecessary. A mounting process also becomes unnecessary because the bus bar is mounted at the same time that the rotor is molded. Further, a mounting base is unnecessary since the bus bar is provided parallel to the upper wall surface of the rotor. That is, the upper wall of the rotor is utilized as a base substrate of the bus bar to reduce the required space of the cable reel.
In another aspect of the present invention, a mounting structure is made simpler, reducing the number of components, assembling processes, and production facilities. Furthermore, because the bus bar is mounted directly on the rotor, the flat cable can be mounted in an accurate position without causing accumulation of dimensional tolerances at the disposed position of the flat cable, thereby making it possible to set a dimension (in height) in an axial direction of the rotor smaller by an amount equivalent to the space that would be required for a mounting case or the like.
In a further aspect of the present invention, a cable reel is provided including an opening is provided on an upper wall of the rotor, which allows a connecting area of the bus bar to be exposed, and a through slit for a flat cable is provided at an inner peripheral end of the opening. An inner peripheral end area of the flat cable is pulled out through the through slit from the annular hollow space and is arranged on the upper face of the bus bar, and conductors of the flat cable and the bus bar are welded from above and below using a welding horn and a welding anvil.
According to another aspect of the present invention, a bus bar that is molded onto the rotor, and a flat cable can be welded together by a welding horn and a welding anvil. In addition, because the bus bar and the flat cable are connected in the area of the starting point for coiling the flat cable, a spare length becomes unnecessary for connecting the bus bar with the flat cable. Furthermore, a connector area projects from the upper wall of the rotor, and a connecting area of the bus bar is exposed through the opening of a bottom area of the connector area. An L-type terminal connected with an external wire terminal is inserted into the connector area, the lower face of the L-type terminal is positioned on the upper face of the bus bar, and the bus bar and the L-type terminal are connected by welding using the welding horn and the welding anvil. Further, by connecting a C-type terminal with the cable terminal, the L-type terminal and the bus bar that is molded in a horizontal position in the rotor are welded by a welding horn and a welding anvil.
According to a further aspect of the invention, the welding area of the conductors of the bus bar and the flat cable, and the welding area of the bus bar and the wire side, are positioned at the same radial distance from the center of the rotor, or circular periphery of the rotor, and welding connection is performed by rotating the rotor relative to a welding horn and a welding anvil. Further, the welding connection between the bus bar and the flat cable and the welding connection between the bus bar and the cable terminal can be performed in succession by rotating the rotor under conditions in which a welding horn of a welding machine that extends from the peripheral edge direction of the upper wall of the rotor and a welding anvil are held at a predetermined position, thereby making the welding work higher in efficiency. Particularly, when there are many welding points required, the present invention exhibits remarkable efficiency in welding work.
According to another aspect of the present invention, an ultrasonic welding machine or a resistance welding machine is normally used for the welding.
According to a further aspect of the present invention, a structure which connects an outer peripheral end of the flat cable and a cable of the body side also includes the same structure as that described above, and, by molding the bus bar on the base surface of the stator, the outer peripheral end of the flat cable and a cable wired to the automobile body side may be weld connected to the bus bar. Furthermore, the stator side may be fastened as usual in an engaged manner to an engaging area provided on the stator by connecting the flat cable that is molded to a different body case and a cable.
In a further aspect of the present invention, a cable reel is provided including a stator and a rotor rotatably connected to the stator, a flat cable is provided in a coiled condition in an annular hollow space formed by the stator and the rotor, the flat cable has an inner peripheral end electrically connected with an external cable through a connector extending from the rotor, an upper wall of the rotor forms an upper wall of the annular hollow space, a bus bar is connected with each conductor on the inner peripheral end of the flat cable and secured to the upper wall of the rotor within an insert mold, and the conductors of the flat cable and an external cable are welded to the bus bar.
According to another aspect of the present invention, a method of making a cable reel is provided, the method including providing a rotor rotatably connected to a stator, the rotor and the stator forming an annular hollow space, and an upper wall of the rotor forming an upper wall of the annular hollow space, providing a flat cable in a coiled condition in the annular hollow space formed by the stator and the rotor, the flat cable having an inner peripheral end, insert molding a bus bar to the upper wall of the rotor, and welding the bus bar to each conductor on the inner peripheral end of the flat cable. The present invention may further include connecting an external cable to the bus bar by welding.
According a further aspect of the present invention, a method of making a cable reel is provided including providing an opening on the upper wall of the rotor, the opening allowing a connecting area of the bus bar to be exposed, providing a through slit for the flat cable adjacent an inner peripheral end of the opening, pulling the inner peripheral end of the flat cable out through the through slit from the annular hollow space and positioning the inner peripheral end of the flat cable on an upper face of the bus bar, and welding the conductors of the flat cable and bus bar together using a welding horn and a welding anvil.
In another aspect of the present invention, a method of making a cable reel is provided including providing a connector area that projects from the upper wall of the rotor so that a connecting area of the bus bar is exposed through an opening of a bottom area of the connector area, providing an L-type terminal connected with an external wire terminal that is inserted into the connector area, wherein a lower face of the L-type terminal is positioned on an upper face of the bus bar, and connecting the bus bar and the L-type terminal by welding using a welding horn and a welding anvil. The present invention may further include a method including positioning a welding area of the conductors of the flat cable and the bus bar, and a welding area of the bus bar and an external cable, on a same radius of the rotor, and rotating the rotor to position a welding horn and a welding anvil of a welding machine to perform the welding.